1. Field of the Invention
This invention relates to an air gun for carrying out firing and blowback with a compressed gas as an energy source, and has a structure for supplying energy for both firing of a bullet and carrying out blowback from a single compressed gas. In more detail, the invention relates to an air gun that performs firing of a bullet and blowback more efficiently than a conventional air gun for firing and carrying out blowback, and with which design of bullet firing and blowback adjustment can be made more simple.
2. Description of the Related Art
A mechanism of a conventional air gun, for firing a bullet using compressed gas and performing blowback, has a single air chamber, and a single valve is provided inside the air chamber. By distributing the gas inside the air chamber for firing use and blowback use, both firing and blowback are carried out by operating the single valve.
For example, as related art 1, U.S. patent application Ser. No. 11/024,479, applied by the present applicant (US application date: Dec. 20, 2004), discloses
“An air gun, comprising:
a slide, provided in an upper part of a gun and capable of sliding parallel to a barrel;
a cylinder section, formed of a cylinder that is open at a muzzle side and closed off at a gun rear end side, fixed inside a gun rear end side of the slide;
a hit pin provided projecting from a hollow inner portion of the cylinder section to a gun rear end side, and being capable of sliding in a nozzle direction;
a hollow valve pin chamber fixed to the gun body so as to be positioned inside the hollow inner portion of the cylinder section;
a valve body having a through hole passing through from a muzzle side to a gun rear end side at a smaller diameter than the valve pin chamber; a gas supply port, opened to a cylindrical peripheral surface of the valve pin chamber, for constantly supplying compressed gas to the valve pin chamber of the valve body;
a valve pin, formed as a cylinder and provided inside the valve pin chamber, constantly urged to the gun rear end side and having a bullet nozzle insertion section formed at a muzzle side and inserted into the muzzle side through holes of the valve pin chamber to project, and a pin body that has a valve pin flange section, capable of sliding in an air-tight state in the muzzle side through hole of the valve pin chamber and contacts a gun rear end side surface of the valve pin in an air-tight manner at the gun rear end side, the valve pin communicating with a muzzle side providing a valve pin chamber side opening that opens to a pin body side surface at a muzzle side of a pressing section provided in the pin body;
a pressing section, provided at a gun rear side of the pin body, fixed to the valve body, inserted into rear end side through holes of the valve pin to project to the gun rear side, positioned so that a tip end of a gun rear side is adjacent to the hit pin, and capable of venting compressed gas from a gap between the rear end side through holes;
a bullet feed nozzle link for linking to a trigger; and
a bullet feed nozzle, formed as a cylinder, inserted into a valve pin muzzle side bullet feed nozzle insertion section projecting to a muzzle side of the valve pin chamber, forming a rib-shaped bullet feed nozzle link engagement projection for engaging with the bullet feed nozzle link at an outer periphery of a gun rear end side, and being capable of sliding in the valve pin muzzle side bullet feed nozzle insertion section in order to load a bullet in the chamber in response to movement of the trigger and the bullet feed nozzle link, wherein
when the hit pin is pressed to the muzzle side and made to slide to the muzzle side, the valve pin slides to the muzzle side against urging force to release an airtight state between the valve pin flange section and a side surface at the gun rear end side of the valve pin chamber, compressed gas supplied to the valve pin chamber from the gas supply port is supplied from between the side surface at the gun rear end side of the valve pin chamber and the valve pin flange section to the valve pin chamber side opening, and a bullet is fired from the muzzle by the supply of compressed gas through the bullet feed nozzle insertion section to the muzzle side of the bullet feed nozzle, and
compressed gas is supplied from a gap between the pressing section and through holes into which the pressing section is inserted to the gun rear end side to cause the cylinder section to move to the gun rear end side.”.
Also, as another embodiment of the invention of related art 1, there is disclosed an air gun as described above in which the cylinder section is provided freely moving inside a gun rear side of the slide, and there is no hit pin.
However, with the mechanism of the air gun disclosed in related art 1, firing and blowback are carried out using discharge of a single valve provided in a single air chamber, and since compressed gas is distributed for firing use and blowback use these actions are carried out at substantially the same time. Therefore, even if it is attempted to independent and separately adjust the firing operation and the blowback operation, this type of independent adjustment is difficult.
Also, with a structure such as that of related art 1, the firing operation and the blowback operation can not be independently adjusted separately at the design stage. That is, since distribution of gas pressure of the compressed gas is difficult, adjustment of bullet speed and adjustment of blowback strength and period, etc. at the time of design is extremely difficult.